- spark plugs
Spark Plug Replacement
Updated 8 Jan 2025
Joel Ilton
How much does car spark plugs cost?
On a standard 4-cylinder engine with standard spark plugs, the replacement cost can start around $175. Other factors to consider are if precious metals are used, such as platinum and iridium, instead of copper.
6-cylinder and 8-cylinder engines will increase in price as more spark plugs are required.
You can find the cost of replacing your car spark plugs from one of our highly recommended specialists.
What do car spark plugs do?
The car spark plugs are one of the most essential components in a petrol internal combustion engine.
Their main job is to ignite the air and fuel mixture inside the cylinders.
The ignition system supplies voltage to the spark plug at specific intervals controlled by the Engine Control Unit or an Ignition module.
They wear out over time, and most manufacturers have specific kilometres and time intervals for replacement.
If they are not replaced, the air-fuel mixture will be harder to ignite, causing the engine to misfire and increasing fuel consumption.
Most engines will have a spark plug for each cylinder, although some manufacturers will use two spark plugs per cylinder.
In some vehicles, removing the intake manifold is required to get to the car spark plugs.
How are car spark plugs replaced?
What are the symptoms of bad car spark plugs?
Common symptoms to look out for when car spark plugs start to fail include the following:
- High fuel consumption
- Increased engine vibration or engine misfire
- Poor engine performance
How often should car spark plugs be changed?
Operating a vehicle that has excessively worn spark plugs can cause other damage, especially if the vehicle is misfiring.
This allows unburned fuel to enter the exhaust and may cause expensive damage to the catalytic converter, as well as expensive internal engine damage.
If you notice any of these symptoms, have your vehicle inspected by one of AutoGuru's 1,600+ qualified workshops, or have a fully certified mobile mechanic come to your house or office – Too Easy!
All data gathered in June 2023.
Written By
Joel Ilton
Finding a passion for cars from a young age, Joel carried out work experience as a mechanic whilst at school before starting an apprenticeship after finishing year 12.
Joel is now the Workshop Manager at Robina Volkswagen.